Mesa produces the finest and most durable stock sets available. The High-tube design is for dedicated optics such as the Eotech and Aimpoint electronic sights. The stock comes with a receiver length Picatinny rail that allows you to adjust the eye relief and position of the sight to your liking. The stock set also includes Mil-spec tube and stock to allow you greater choice of aftermarket stocks without the need to replace the tube. The adapter has stainless steel inserts helicoiled for strength and durability. The mounting points allow you to attach rails and shell carriers directly to the adapter. All of Mesa's Products are manufactured to the highest quality and to stand up to every day use by the most rugged of operators.